series 80 has a pin that slides up from the frame into the slide. to disassemble you have to make sure the rear safety is not engaged. its a firing pin type safety. when the rear safety is not engaged the trigger cant be pulled and the firing pin is prevented from forward movement.
series 70 pistols dont have this mechanism. fairly new development, i believe, and is currently a requirement in ca.
to disagree with another post, the colts generally have higher tolerances than the others. being milled and hand fitted, also take a bit longer to break in.
being milled, they are also stronger, technically, and the consistency of the metal in the parts is better.
most kimbers are cast, some springfields are milled, all colts are milled.